[mlir] fix the Disambiguate NoneType in OpDefinitionsGen (#172923)

Qualify NoneType as mlir::NoneType in recordToType to avoid ambiguity
when other headers introduce a different NoneType symbol. This fixes
build failures seen when enabling tblgen-to-irdl in certain downstream
configurations

The ambiguity is between:


[llvm::Nonetype](https://github.com/intel/llvm/blob/sycl/llvm/include/llvm/ADT/None.h#L26)
and
[mlir::Nonetype](https://github.com/llvm/llvm-project/blob/main/mlir/tools/tblgen-to-irdl/OpDefinitionsGen.cpp#L125)

Both are visible due to `using namespace mlir` and `using namespace
llvm` in the file.

Fixes: https://github.com/llvm/llvm-project/issues/160537

mlir/tools/tblgen-to-irdl/OpDefinitionsGen.cpp

@@ -122,7 +122,7 @@ static std::optional<Type> recordToType(MLIRContext *ctx,
   }
 
   if (predRec.getName() == "NoneType") {
-    return NoneType::get(ctx);
+    return mlir::NoneType::get(ctx);
   }
 
   if (predRec.getName() == "BF16") {